Dynamic magnetic information storage or retrieval – Head mounting – Disk record
Reexamination Certificate
2000-09-19
2003-02-04
Evans, Jefferson (Department: 2652)
Dynamic magnetic information storage or retrieval
Head mounting
Disk record
C360S245800
Reexamination Certificate
active
06515832
ABSTRACT:
The invention described and claimed herein relates generally to hard disk drives used to store information in computers and particularly to an improved suspension assembly used in such hard disk drives.
BACKGROUND OF THE INVENTION
Most personal computers today utilize direct access storage devices (DASD) or rigid disk drives for data storage and retrieval. Presently, a disk drive includes at least one disk that has a selectively magnetizable magnetic coating. In addition, a disk drive will include a read/write “head” that is positioned a microscopic distance from the disk surface. During operation, the read/write head is said to “fly” over the disk as the disk is rotated at speeds currently ranging from 3600 revolutions per minute (rpm) to 15,000 rpm. Information is stored on or written to the disk by the selective magnetization of the disk's magnetic coating and is retrieved or read from the disk by sensing the previous selective magnetizations. The read/write head is affixed to the disk drive by a suspension assembly and electrically connected to the disk drive electronics by an electrical interconnect. This structure (suspension, electrical interconnect, and read/write head) is commonly referred to in the industry as a Head Gimbal Assembly, or HGA. The read/write head, along with a slider, is disposed at the distal end of an electrical interconnect/suspension assembly.
More specifically, currently manufactured and sold read/write heads include an inductive write head and a magneto resistive (MR) read head or element or a “giant” magneto resistive (GMR) element to read data that is stored on the magnetic media of the disk. The write head writes data to the disk by converting an electric signal into a magnetic field and then applying the magnetic field to the disk to magnetize it. The MR read head reads the data on the disk as it flies adjacent to it. To do this, a “sense” current is sent through the read head. As the read head passes over the varying magnetized areas on the disk surface, a current will be induced in the read head according to well-known electromagnetic principles. This will result in a change in the sense current, which is accompanied by a change in the current voltage. The changes in the sense current or the sense current voltage in turn is converted into a binary data stream.
An exploded view of a typical electrical interconnect/suspension assembly is shown in
FIG. 1
, which illustrates several components including a suspension A and an interconnect B. It will be understood that the actual physical structures of these components may vary in configuration depending upon the particular disk drive manufacturer and that the assembly shown in
FIG. 1
is meant to be illustrative of the prior art only. Typically, the suspension A will include a base plate C, a radius (spring region) D, a load beam E, and a flexure F. At least one tooling discontinuity G may be included. An interconnect B may include a base H, which may be a synthetic material such as a polyimide, that supports typically a plurality of electrical traces or leads I of the interconnect. The electrical interconnect B may also include a polymeric cover layer that encapsulates selected areas of the electrical traces or leads I.
Stated otherwise, suspension A is essentially a stainless steel support structure that is secured to an armature in the disk drive. The read/write head is attached to the tip of the suspension A with adhesive or some other means. The electrical interconnect B is terminated, that is, electrically connected, to bond pads on the read/write head and provides an electrically conductive path between the disk drive electronics at one end thereof and the read and write elements in the read/write head at the other end thereof. The electrical interconnect is usually comprised of individual electrical conductors supported by an insulating layer of polyimide and typically covered by a cover layer.
Successful operation of a hard disk drive is dependent upon many factors. Among them are the fly height and the geometric and physical characteristics of the HGA.
As mentioned previously, the slider is spaced a small distance, or fly height, apart from the spinning disk. The fly height must be controlled within a narrow range for the disk drive to operate successfully. As the fly height increases, the ability of the read/write head to read or write data to the disk diminishes; as the fly decreases, the slider can more easily hit the disk surface, commonly known as a “crash” or as “crashing the drive” and resulting in the permanent loss of stored data.
The fly height of the slider is partly determined by the characteristics of the head suspension assembly to which it is mounted. One of these characteristics is the vertical load, commonly referred to as the “gram load”, imparted on the slider by the head suspension assembly. This vertical or gram load is directed normal to the surface of the disk in order to oppose the “lift” forces created by the air passing between the slider and the spinning disk. In other words, as the slider flies relative to the disk, the air flowing between the slider and the disk results in the creation of a lifting force that tends to push the slider away from the disk. The gram load is provided to counter those lift forces. This balancing of opposing forces is a delicate task since the fly height must be maintained within the desired range. As a result, head suspension assemblies are manufactured with a very precise gram load, typically with a tolerance of +0.2 grams.
Another factor determining slider fly height is the relative position of the head suspension assembly load center relative to the slider air bearing geometry. If this load center or “load point” is mis-aligned relative to the air bearing surface of the slider, an undesired torque is placed on the slider, which can cause an undesired slider pitch and/or roll. If the slider pitches or rolls, the spacing of the read/write element from the disk surface will be affected because the pitching or rolling motion of the slider changes its orientation and thus the orientation of the read/write elements relative to the disk surface.
Yet another head suspension assembly characteristic that can have a significant effect upon the fly height of a slider is referred to as “static attitude.” Static attitude is the angular attitude of the gimbal to which the slider is mounted relative to disk surface. Typically, head suspension assemblies are manufactured with tolerances for static attitude approaching +30 arc-minutes and the gimbal stiffnesses are designed to be very low (or highly compliant) to allow the slider air bearing forces to correct for static attitude tolerances during operation. If the static attitude is outside the desired range, a torque can be imparted to the slider, which as previously noted, can create an undesired slider pitch and/or roll.
Successful reading or writing of data between the head and the spinning disk also requires that the head be precisely positioned relative to the location on the disk from which data is to be read or to which data is to be written. Presently, data is written to hard drives along circular “tracks” on the disk. If a mode of vibration in the load beam or gimbal creates or causes motion that in turn prompts the read/write element to move off the track to be read or written to, the hard drive's ability to follow the data tracks, and thus read and write to the disk properly, will be compromised. Specifically, to resist off-track motion, the side to side or lateral gimbal stiffness is desirably kept high in the gimbal area. As such, great care is taken to design and manufacture head suspension assemblies so as to optimize the suspension's vibrational, or resonant, performance. Traditionally, there exists a trade-off between the desire for high lateral stiffness and the desire for low pitch and roll stiffnesses.
During gimbal manufacture and use, gimbal vertical stiffnesses are desired to be high, thereby enabling the head suspension assembly to resist han
Applied Kinetics Inc.
Evans Jefferson
Kagan Binder PLLC
LandOfFree
Gimbal stiffness control for head suspension assemblies does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Gimbal stiffness control for head suspension assemblies, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Gimbal stiffness control for head suspension assemblies will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3151761